Forces Flashcards
What do scalar quantities have
Magnitude only
What do vector quantities have
Magnitude and an associated direction
How can the vector quantity be represented
As an arrow.
the length of the arrow=magnitude
the direction of the arrow=direction of the vector quantity
What is Force
A push and pull that acts on an object due to the interaction with another object
What are all forces between objects due to
Contact forces - the object are physically touching
Non-contact forces - the objects are physically separated
What type of quantity is force
Vector quantity
Give examples of contact forces
Friction
air resistance
tension
normal contact force 
Give examples of noncontact forces
Gravitational force
electrostatic force
magnetic force
What is the force of gravity due to
The gravitational field all around the Earth
What does the weight of an object depend on
The gravitational field strength at the point where the object is
What is the weight of an object on the mass of an object
Directly proportional
How is weight measured
Using a calibrated spring balance ( a Newton meter)
What is the single force called
The resultant force
What does magnitude mean
Size
The weight of an object is directly proportional to the mass what does this mean
If we double the mass the weight will double
The weight of an object may be considered to act at a single point what is this called
The center of mass
Weight is the force acting on an object what is this due to
Gravity
What might the number of forces acting on an object be replaced by
A single force that has the same effect as the original forces acting together
What can a single force be resolved into
Two components acting at right angles to each other
(the two components force work together have the same affect as the single force(Single force=resultant force))
If the forces are balanced what does it mean
The resultant force is zero

When a force causes an object to move through a distance what does this mean
Work is done on the object
So a force does work on an object when the force causes a displacement of the object
What does work done against the friction forces acting on an object cause 
It causes a rise in the temperature of the object
1 joule = ? Newton-meter
1 Newton meter
1 joule of work done when a force of one Newton causes a displacement of 1 m
What will happen to elastic materials if we take away the force acting on them
It will return back to the original length or shape
What is an elastic deformation and inelastic deformation
Elastic returns to its original shape after force has been applied
Inelastic doesn’t return back to its shape after force has been applied
Required practical: describe how to investigate the relationship between force and extension for a spring
..
What does linear mean
Straight line
What is distance
How far an object moves.
distance does not involve direction meaning it’s a scalar quantity
What is displacement
Both the distance an object moves measured in a straight line from the start to the finishing points in the direction of the straight line meaning displacement is a vector quantity
What does speed not involve
Direction meaning speed is a scalar quantity
What does the speed of a person depend on
Age, fitness and distance traveled
What’s the speed of a person walking running and cycling
Walking 1.5 m/s
running 3 m/s
cycling 6 m/s
What is the typical value of speed of sound in air
330 m/s
What’s the speed of the car on the main road, a fast train in UK and a cruising aeroplane 
Car on the main road 13 m/s
fast train in the UK 50 m/s
cruising aeroplane 250 m/s
What is velocity
The velocity of an object is its speed in a given direction meaning it’s a vector quantity
What changes in a circular motion that involves a constant speed
The velocity keeps changing
An object that slows down is called
Deceleration
When any objects falls towards the surface of earth it accelerates around what
9.8 m/s squared
When the object stops accelerating and moves at a constant velocity what is this called
Terminal velocity
What happens to an object falling through a fluid
It’s accelerates due to the force of gravity eventually the resultant force will be zero and the object will move at its terminal velocity
The velocity of an object will only change when
A resultant force is acting on the object
What is newtons first law of motion
If the object is stationary it will remain stationary
If the object is moving it will continue to move at the same speed and in the same direction so the object continues to move at the same velocity
What is balanced when a vehicle travels at a steady speed
The resistance forces
they including friction with the air and friction with the road 
What is the Object that stays stationary or continues moving at the same speed and direction unless a resultant force is applied called
Inertia
What is newtons second law
The acceleration of an object is proportional to the resultant force acting on the object and inversely proportional to the mass of the object
What is newtons third law
Whenever to objects interact the forces are exerted on each other are equal and opposite
What is the stopping distance of a vehicle
The sum of the distance the vehicle travels during the drivers reaction time and the distance it travels under the breaking force for a given breaking force the greater
(the speed of the vehicle the greater the stopping distance)
What is the typical value of the reaction time from person to person
0.2 to 0.9 seconds
What can the drivers reaction time be affected by
Tiredness
drugs
alcohol
distractions may also affect the drivers ability to react
What is the braking distance of a vehicle affected by
The road
the weather conditions
the poor condition of the vehicle
What is the inertial mass
A measure of how difficult it is to change the velocity of an object
(It’s defined as: the ratio of force/acceleration)
What type of road conditions cause the braking distance of vehicle to change
Icy or wet conditions
And for the car it’s limited to the brakes or tyres
Required practical: How to investigate the mass and force affects acceleration
Set of a toy car that is attached to a string and the string is looped around a pulley that is attached to a 100g mass
The weight of the mass will provide a force acting on the toy car
Do you need a timer and using chalk drawing lines at equal lengths
Hold the toy car at the starting point and let go of the car
Because there is a force with the string the car will accelerate along the bench
Records the time that the car passes each distance
You could record the experiment on her mobile phone and play the video back to records accurate times
Then repeat the experiment but decrease the mass on the end of the string
The object is the toy car the string and the mass attached to the string all as 1
What happens when force is applied to the break of the vehicles
Work is done by friction force between the brakes on the wheels reduces the kinetic energy of the vehicle and the temperature of the brakes increases
Degree to the breaking force what happens to the deceleration
The deceleration of the vehicle is greater larger decelerations may lead to the brakes overheating or loss of control
What happens to the momentum in a close system
The total momentum before an event is equal to the total momentum after the event
What is conversion of momentum
In a close system the total momentum before and after is equal
